diencephalon

Hypothalamus Structure

• Consists of the optic chiasm, optic tracts, tuber cinereum, infundibulum, pituitary gland, hypothalamus, and mammillary bodies.

Functions of the Hypothalamus

• Controls the thyroid, suprarenal gland, ovary, testis, mammary gland, bone, and fat tissue through the tuberoinfundibular tract.
• Regulates water balance in the body and contractions of the uterus during delivery through the supraopticophyseal tract.

Nuclei of the Hypothalamus

Anterior Group

• Supraoptic nucleus
• Paraventricular nucleus
• Preoptic area (nucleus)
• Suprachiasmatic nucleus, which regulates the body's circadian rhythm and sleep-wake cycle.

Middle Group

• Infundibular nucleus
• Ventromedial nucleus
• Dorsomedial nucleus
• Lateral nucleus
• Tubero-mamillary nucleus

Posterior Group

• Medial mamillary nucleus
• Lateral mamillary nucleus
• Mamillary intercalate nucleus
• Premamillary nucleus
• Posterior area, responsible for memory and spatial navigation.

Third Ventricle Structure

• Superior wall: Tela choroidea, corpus callosum, and fornix.
• Anterior wall: Lamina terminalis, Anterior commissure, Free part of the columns of fornix, Triangular recess, Optic recess.
• Inferior wall: Optic chiasm, infundibulum, tuber cinereum, mammillary bodies, subthalamus, and crura of the brain and tegmen of mesencephalon.
• Posterior wall: Pineal body, habenular commissure, and posterior commissure.
• Lateral wall: Thalamus, hypothalamic sulcus, interventricular opening, interthalamic adhesion, and transverse fibers.

Midbrain Structure

• Formed by the Lamina tecti (Tectum), Aqueduct, and Cerebral Peduncles, which consist of the Cerebral crura (anteriorly) and the Tegmentum (posteriorly).
• Lamina tecti components: Superior colliculi and Inferior colliculi.

Diencephalon Structure

• Components: Thalamoencephalon, Hypothalamus, Subthalamus, Third ventricle.
• Thalamoencephalon subdivisions: Thalamus, Metathalamus, Epithalamus.

Thalamus Structure

• Superior surface covered by a layer of white matter called stratum zonale.
• Inferior surface covered by the hypothalamic region.
• Lateral surface covered by the capsular region covered by reticular zone.
• Medial surface covered by the wall of the third ventricle covered by central grey matter.
• Nuclei: Anterior, paraventricular, supraoptic, suprachiasmatic, medial, lateral (ventral and dorsal groups), reticular, intralaminar, centromedian, habenula, lateral and medial geniculate bodies, pulvinar.

Epithalamus Structure

• Components: Habenular trigone, Habenula, Habenular commissure, Posterior commissure, and Pineal body.
• Pineal body location: Above the superior colliculi of the midbrain.
• Pineal body connections: Superiorly, the habenular commissure; inferiorly, the posterior commissure.
• Pineal body malfunction effects: Premature and incomplete or delayed puberty.

Metathalamus Structure

• Components: Lateral geniculate body and medial geniculate body.

Hypothalamus Functions

• Controls the endocrine system, fluid balance, body temperature, feeding behavior, and sexual activity.